JP3078373B2 - Photoelectric conversion device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device such as a solar cell and a pin type photodiode, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices using non-single-crystal silicon (here, non-single-crystal silicon is hydrogenated amorphous silicon or microcrystalline silicon) have been actively developed. In particular, solar cells and photodiodes capable of producing large-area products at low cost have been vigorously developed.

[0003] As a method of depositing hydrogenated amorphous silicon or microcrystalline silicon used in these semiconductor devices, RF plasma CVD or microwave plasma CVD using silane SiH ₄ or disilane Si ₂ H ₆ as a deposition gas is used. Alternatively, a reactive sputtering method in which an Si target is sputtered in an Ar plasma in the presence of hydrogen gas has been used. Experimentally, in addition to this,
There are reports such as a VD method, an ECRCVD method, and a vacuum deposition method of Si in the presence of hydrogen atoms, and there are also successful examples of a thermal CVD method using disilane Si ₂ H ₆ or the like.

The most widespread method for depositing such a hydrogenated amorphous silicon film or microcrystalline silicon film is a plasma CVD method. In this method, silane (SiH ₄ ) and disilane (Si ₂ H ₆ ) are often used.
Using gas, dilute with hydrogen gas if necessary
Plasma is generated at a high frequency of 3.56 MHz, and the film-forming gas is decomposed by the plasma to produce reactive active species, and the film is deposited on the substrate. When a doping gas such as phosphine (PH ₃ ), diborane (B ₂ H ₆ ), or BF ₃ is mixed with a deposition gas, an n-type or p-type hydrogenated amorphous silicon film or a microcrystalline silicon film can be formed. Therefore, various devices can be made using these films.

FIG. 3 shows an example of a conventional typical solar cell manufactured using these methods.

In FIG. 1, reference numeral 301 denotes a substrate;
2 is a base electrode. Reference numeral 303 denotes an n ⁺ -type hydrogenated amorphous silicon layer, 304 denotes an i-type hydrogenated amorphous silicon layer, 305 denotes a p ⁺ -type hydrogenated amorphous silicon layer, and 306 denotes a transparent electrode.

Light passes through the transparent electrode and passes through the p ⁺ layer 305.
Incident from This device has a pin structure, and the carriers generated by the light absorbed by the i-layer 304 are such that, due to the internal electric field, the electrons are on the n ⁺ layer 303 side and the holes are on the p-layer 303 side.
Each drifts toward the ⁺ layer 305, and as a result, an electromotive force is generated between p ⁺ and n ⁺ .

[0008]

However, the above-mentioned prior art has the following problems to be solved.

FIG. 5 is an energy band diagram of the conventional solar cell. In the figure, A is the p ⁺ region, B is i
Type hydrogenated amorphous silicon layer, D indicates an n ⁺ region, and F indicates a Fermi level. In the case of such a conventional single cell, the optical band gap of the undoped layer is about 1.8 eV, and light in a long wavelength region having a smaller energy is not effectively used, and the conversion efficiency is low. There was a disadvantage that it did not improve as expected.

[0010] In order to solve the drawback, it has been conventionally proposed to use a layer having a different optical band gap to form a heterostructure. This is because a short wavelength light has a large absorption coefficient, so that a hydrogenated amorphous silicon layer having a large optical band gap is disposed as a first layer on the light incident side as a photoelectric conversion layer. Light is absorbed, and then, as a second layer, a layer having a small optical band gap such as hydrogenated amorphous silicon germanium is disposed as a photoelectric conversion layer, and a layer having a small absorption coefficient not absorbed by the first layer is provided. It is intended to efficiently absorb light on the wavelength side.

Conventionally, in such a heterostructure configuration,
An alloy such as hydrogenated amorphous silicon carbide is used as a material having a wide optical band gap, and an alloy such as hydrogenated amorphous silicon germanium is used as a material having a narrow optical band gap.

However, in such an alloy-based semiconductor, many defects are generated in the film at the time of film formation, whereby photo carriers generated by light vigorously recombine, and the amount of current that can be extracted to the outside as a current decreases. As a result, there is a problem that the conversion efficiency is not improved as expected.

[0013] In addition, the production of a device having a heterostructure using alloys of such different materials leads to complication of the production process, and also has the disadvantage of increasing the production cost.

[0014]

According to the present invention, as a means for solving the above-mentioned problems, a semiconductor layer of a first conductivity type and a doped layer provided on the semiconductor layer of the first conductivity type are provided. A non-doped silicon layer, an undoped hydrogenated amorphous silicon layer provided on the silicon layer, and a second conductivity type different from the first conductivity type provided on the hydrogenated amorphous silicon layer. A semiconductor layer;
Having a configuration in which light is incident from the semiconductor layer side of the second conductivity type , wherein the undoped silicon layer has an optical band gap of the undoped hydrogenated amorphous silicon layer. Manufacturing method of photoelectric conversion device with microcrystalline silicon layer narrower than optical band gap
Depositing non-single-crystal silicon in the method,
Exposing the deposited non-single-crystal silicon to atomic hydrogen,
Alternately to form the microcrystalline silicon layer.
You.

The present invention also relates to a method for manufacturing the above photoelectric conversion device.
Depositing non-single-crystal silicon.
Exposing the deposited non-single-crystal silicon to atomic hydrogen,
Repeatedly and alternately to form the microcrystalline silicon layer
The present invention also provides a method for manufacturing a photoelectric conversion device.

[0016]

According to the present invention, an undoped microcrystalline layer is provided on a layer having an n.sup. ⁺ (Or ^{p.sup. +} ) Type semiconductor of a first conductivity type, and undoped hydrogenated amorphous silicon is further provided. A photoelectric conversion device having a structure in which a layer is provided and a layer having a p ⁺ -type (or n ⁺ -type) semiconductor of the second conductivity type is provided, and this microcrystalline silicon is used as a material having a narrow optical band gap. ,
The sensitivity on the long wavelength side can also be improved.

Further, in the above-described method for manufacturing a photoelectric conversion device, a step of depositing the microcrystalline layer with a non-single-crystal silicon or microcrystalline silicon layer on a substrate, and exposing the deposited layer to atomic hydrogen. By making the film deposition method while repeating the steps alternately, more efficient,
And an effective manufacturing method can be provided.

In the present invention, a narrow optical bandgap material, which has been conventionally insufficiently realized by an alloy such as hydrogenated amorphous silicon germanium, is more effectively realized by microcrystalline silicon.

The microcrystalline silicon has a structure in which microcrystalline grains and amorphous silicon are mixed. In the portion of the fine crystal grains, the hydrogen concentration is reduced, and the entire film is in a state where the hydrogen concentration is low. Looking at the optical band gap of this microcrystalline silicon, it can be seen that it changes according to the hydrogen concentration in the film.

If such microcrystalline silicon is used as a narrow optical bandgap material and integrally with the hydrogenated amorphous silicon layer, a device can be manufactured without complicating the manufacturing process. Then, since the crystallization has progressed to some extent, the carrier mobility is improved. As a result, the photocurrent also increases.

However, in general microcrystals,
Since the carrier recombination at the grain boundary portion is active, there is almost no photoconductivity. Therefore, it is difficult to use as it is as a photoelectric conversion layer having a narrow optical band gap.

Therefore, if a repetitive film forming method of the present invention in which the film is formed while repeating the film formation and the atomic hydrogen exposure is used, as will be described in detail later, hydrogen in the film or the crystal grain size when microcrystallized. Can be freely controlled by the film formation time or the atomic hydrogen exposure time when a unit film (film formed by one unit when one deposition and atomic hydrogen exposure are considered as one unit process), and the fine crystal grains can be controlled. Field defects can be reduced. Therefore, if microcrystalline silicon is formed using this method, sufficient photoconductivity can be generated. Therefore, this can be used for the photoelectric conversion layer as a narrow optical band gap material.

Further, according to the present method, since a process from a hydrogenated amorphous silicon film to microcrystalline silicon can be performed simply by setting a time parameter without largely changing process conditions such as switching of source gas, etc. The manufacturing process is considerably simplified compared to the prior art. This is a great advantage when actually forming a film.

[0024]

(Embodiment 1) FIG. 1 shows an embodiment in which an intrinsic microcrystalline silicon layer is formed by using the film forming method according to the present invention, and a photoelectric conversion device (a solar cell in this embodiment) is formed. FIG. 4 is a schematic sectional view showing a structure, and FIG. 4 shows an energy band profile thereof.

In FIG. 1, reference numeral 101 denotes a substrate;
2 is a base electrode. 103 is an n ⁺ type (first conductivity type) hydrogenated amorphous silicon layer, 104 is an i-type microcrystalline silicon layer, 105 is an i-type hydrogenated amorphous silicon layer,
106 is a p ⁺ type (second conductivity type) hydrogenated amorphous silicon layer, and 107 is a transparent electrode.

Light enters from the p ⁺ layer 106 through the transparent electrode 107. This embodiment has a pin structure, i
The carriers generated in the layer 105 are generated by an internal electric field.
Electrons are on the n ⁺ layer 103 side, holes are on the p ⁺ layer 106 side,
Each drifts, and as a result, an electromotive force is generated between p ⁺ and n ⁺ .

Hereinafter, a procedure for depositing the microcrystalline silicon layer 104 of the present invention will be described. In the following description, it is assumed that atomic hydrogen is generated by hydrogen plasma and is used.

In this embodiment, after depositing a hydrogenated amorphous silicon layer for a time t _D , the deposited film is irradiated with atomic hydrogen plasma (exposure to atomic hydrogen) for a time t _A. The film is formed while repeating a set of steps.

That is, during t _A, the surface of the deposited film is exposed to atomic hydrogen in the hydrogen plasma. At this time, the atomic hydrogen in the hydrogen plasma diffuses into the deposited film or to some extent on the deposited surface. It is considered that the rearrangement of the Si network occurs while activating the silicon atoms, and as a result, hydrogen in the film is eliminated. Moreover, it is considered that the film structure is extremely relaxed due to the rearrangement, and as a result, the amorphous phase is changed to the microcrystalline phase.

The effect of the hydrogen plasma at that time will be described.
FIG. 9 shows the relationship between the hydrogen concentration in the film and the substrate temperature Ts when the unit film formation time t _D and the hydrogen plasma irradiation time t _A are kept constant.

FIG. 9A shows the case where the film is not repeatedly formed (the conventional continuous film formation).

B is a case where the film is formed by repeated film formation starting from the condition of amorphous silicon (however, the conditions of t _D and t _A at this time are such that crystallization is likely to occur. That is, t _D is short and t _A is long.)

Starting from conditions close to those of microcrystalline silicon (microcrystallization does not occur in the state of a continuous film; specifically, a condition in which the dilution ratio of hydrogen gas is large). This is a case where a film is formed by repeated film formation. The portions marked with M in the figures b and c are regions where crystallization has occurred.

The thickness of the unit film deposited during the unit film formation time t _D is preferably about several atomic layers.
In practice, it is desirable to be about 10 °. If the newly deposited layer is too thick, the relaxation of the silicon network is unlikely to occur, and the effect of hydrogen plasma irradiation does not appear.

FIG. 10 shows the dependence of the hydrogen concentration in the film on the irradiation time t _A with hydrogen plasma. a indicates that the film thickness in each cycle is 50
Ｂ, and b is the case of a film thickness of 100Å. The area marked with M in the figure of a is an area where microcrystallization has occurred. As shown in the figure, the film thickness in each step is 1
If the temperature is not less than 00 ° (b), no matter how much hydrogen plasma irradiation is performed, the structural relaxation does not progress, and crystallization does not occur while maintaining the amorphous phase. Therefore, the film thickness deposited during t _D must be 50 ° or less (a), preferably 10 ° or less.

FIG. 11 shows the relationship between the deposited film thickness during t _D and the hydrogen concentration in the film. In the figure, M is a region where crystallization has occurred. It can be seen that the effect of the hydrogen plasma decreases when the deposited film thickness during t _D is 50 ° or more.

FIG. 12 shows the relationship between the crystal grain size determined by X-ray diffraction and the irradiation time t _A of hydrogen plasma. The film condition is a condition that facilitates crystallization (hydrogen dilution condition). It can be seen that when the irradiation time of the hydrogen plasma is increased, the crystal grain size grows.

FIGS. 10 and 11 show that the unit film forming time t
_{D. It} can be seen that the hydrogen concentration in the film and the crystal grain size can be controlled by controlling the irradiation time t _A of the hydrogen plasma.

FIG. 13 shows the relationship between the hydrogen concentration in the hydrogenated amorphous silicon layer and the microcrystalline silicon layer formed by the film forming method of the present invention and the optical band gap. As the hydrogen concentration in the film decreases, the optical band gap also decreases.

The film forming conditions in these figures are the same as the following i-layer film forming conditions in the following solar cell prepared by the apparatus shown in FIG.

In this embodiment, the method for producing atomic hydrogen is as follows.
Although hydrogen plasma was considered, any type of hydrogen plasma can be used as long as it can efficiently generate atomic hydrogen. In general, if a capacitively coupled or inductively coupled high-frequency glow discharge is used, this can be realized by a conventional apparatus, and the hydrogenated amorphous silicon film deposited on the substrate is placed together with the substrate in a hydrogen gas glow discharge, By placing it near, atomic hydrogen can be supplied to the deposited film. In addition, there are a method of generating atomic hydrogen by microwave plasma and diffusing it to the surface of the deposited film, and a method of generating atomic hydrogen by ECR plasma.

If a plasma CVD method is employed as a method of depositing a unit film, hydrogen plasma can be generated using the same apparatus, and the film forming method of the present invention can be realized very easily.

FIG. 8 shows a film forming apparatus for realizing the present invention.

In FIG. 8, reference numeral 800 denotes a reaction chamber;
01 is a substrate, 803 is an anode electrode, 802 is a cathode electrode, 804 is a heater for heating a substrate, 805 is a ground terminal, 806 is a matching box, and 807 is 13.56.
MHz RF power supply, 808 and 814 are exhaust pipes, 8
09 and 815 are exhaust pumps, 810 is a hydrogen gas introduction pipe, 811 and 812 are film formation gas introduction pipes, 813 is a three-way valve, 820, 830, 840, 850, and 86.
Reference numerals 0, 822, 832, 842, 852 and 862 denote valves, and 821, 831, 841, 851 and 861 denote mass flow controllers. Deposition gas introduction pipe 81
1 is provided with a three-way valve 813, and by switching the three-way valve 813, ON / OFF of the film forming gas is performed.
Turn OFF. Hydrogen (H ₂ ) is from 862 side, silane (SiH ₄ ) is from 822 side, and diborane (B ₂ H ₆ ) is 8
From the 32 side, phosphine (PH ₃ ) is introduced from the 842 side. In this device, hydrogen is always flowing. Further, SiH ₄ , which is a film forming gas at the time of unit film deposition, or S
Both ON and OFF control of the flow of i ₂ H ₆ alone can easily switch both unit film deposition and hydrogen plasma irradiation.

If the ratio of the film forming gas to the hydrogen gas is too low, crystallization is likely to occur during irradiation with hydrogen plasma. Becomes However, when a hydrogenated amorphous silicon layer is formed on a microcrystalline silicon layer under the same conditions as in the present invention,
If the hydrogen dilution rate is excessively increased, the characteristics of the hydrogenated amorphous silicon film of the continuous film deteriorate. Therefore, the conditions need to be optimized.

In this case, it is also possible to keep the plasma intact in both the step of depositing the unit film and the step of irradiating with the hydrogen plasma. In this case, the film quality during the plasma generation period is poor. Film deposition can be prevented. In this case, it is also preferable to add Ar for plasma stabilization.

Next, the steps of manufacturing the photoelectric conversion device shown in FIG. 1 according to the present invention will be described. Each film was formed using the apparatus shown in FIG.

First, a lower electrode 102 is formed on a glass substrate 101 having a polished surface using a metal film such as Al, and then attached to a cathode in a reaction chamber 800.
The air was sufficiently exhausted by an exhaust pump 809 to 10 ^-6 Torr. The substrate temperature was 250 ° C.

The three-way valve 813 is connected to the film forming gas introduction pipe 411.
And 412 are connected, and then the valves 820, 8
22 is opened, SiH ₄ gas flows at 30 sccm, and the valve 8 is opened.
60,862 the open H ₂ gas is flowed 30sccm, H ₂
The PH ₃ gas diluted to 1% with the gas is supplied to the valves 840, 8
42 was opened and the flow was 30 sccm.

The chamber pressure was set to 1.0 Torr and
0 mW / cm ² of RF power was introduced, discharged 7 minutes n ⁺
Type hydrogenated amorphous silicon layer 103 was deposited at 400 °.

After closing each valve and stopping gas supply, the chamber was evacuated to 10 ^-6 Torr or less.

Next, the microcrystalline silicon layer 104 and subsequently the hydrogenated amorphous silicon layer 106 are deposited by the film forming method according to the present invention. The substrate temperature was kept at 250 ° C.
Hydrogen plasma discharge by RF discharge was used to produce atomic hydrogen.

First, the valves 860 and 861 were opened, and 170 sccm of H ₂ gas was flown into the reaction chamber. After connecting the three-way valve 813 between the film forming gas introducing pipe 811 and the exhaust pipe 814, the valves 820 and 822 are opened, and the SiH ₄ gas 30 sccm is supplied to the film forming gas introducing pipe 811.
Shed. The pressure at this time was 0.5 Torr. In this state, an RF power of 50 mW / cm ² was applied to start hydrogen plasma discharge.

Next, by switching the three-way valve 813, film formation and hydrogen plasma irradiation were repeated. The film forming time t _D in this example is constant at 10 seconds, the film thickness is 10 °, and the hydrogen plasma irradiation time t _A is shown in FIG.
The crystallite size was set to be approximately 300 °.

The defects at the crystal grain boundaries of the microcrystalline silicon formed by this method were reduced, and sufficient photoconductivity was generated. However, the crystal grain size needs to be optimized, and if it is too small, the total area of the crystal grain boundaries increases, and although recombination at the interface decreases, recombination here increases, The original effect cannot be exhibited. During the actual film formation, the opening and closing of the three-way valve was controlled by a computer. The total number of steps was 100, and the thickness of the microcrystalline layer was 1000 °. At this time, the hydrogen concentration in the film was 1%.

After the hydrogen plasma discharge in the final step was completed, the valve 813 was switched, and SiH ₄ was introduced into the chamber. Thereafter, a discharge is started, and a hydrogenated amorphous silicon layer is continuously formed at 3000 °. At this time, it is preferable to form the film continuously while maintaining the discharge. At this time, the optical band gap of the hydrogenated amorphous silicon layer was 1.8 eV. The hydrogen dilution ratio in this example was SiH ₄ / H ₂ = 3/17, and the photoelectric characteristics of the continuous film were good.

Next, ap ⁺ type layer 106 was formed. After closing the valves 820 and 822 and closing the valves 860 and 862 to stop the silane gas and the hydrogen gas, the chamber was evacuated to a degree of vacuum of 10 ^-6 Torr or less. Substrate temperature 2
After changing to 00 ° C., SiH ₄ flowed gas 10sccm and H ₂ B ₂ H ₆ gas 10sccm and H ₂ gas 100sccm diluted to 1% with the gas, while maintaining the pressure to 1 Torr,
The temperature was maintained until the substrate temperature became constant.

Thereafter, an RF power of 50 mW / cm ² is applied, plasma discharge is performed for 10 minutes, and the p ⁺ -type layer is
0 ° was formed. After closing each valve and stopping the gas, the inside of the chamber was evacuated to 10 ^-6 Torr or less.

Finally, a transparent conductive film (IT
O film) 107 was formed at 700 °.

FIG. 4 shows the band profile of the photoelectric conversion device of the present invention. In FIG. 4 , A is a p ⁺ region, and B is i
Type hydrogenated amorphous silicon layer, C indicates a microcrystalline silicon layer, D indicates an n ⁺ region, and F indicates a Fermi level.

The optical band gap of the undoped hydrogenated amorphous silicon layer was 1.8 eV, and the optical band gap of the undoped microcrystalline layer was 1.55 eV. It is assumed that sunlight enters from the p ⁺ layer side, and the short wavelength side is absorbed by the hydrogenated amorphous silicon layer. Light on the long wavelength side that is not sufficiently absorbed by the hydrogenated amorphous silicon layer is absorbed by the microcrystalline silicon.

FIG. 6 shows a conventional single cell (a in the figure).
And the spectral sensitivity in the case of the present invention (b in the figure). It can be seen that the sensitivity on the long wavelength side is improved in the solar cell (b in the figure) having the configuration of the present invention.

FIG. 7 shows the VI characteristics under a light quantity of 100 mW in the case of the conventional single cell (a in the figure) and the case of the present invention (b in the figure). In the present invention, I _SC (short circuit current) was improved, and as a whole, conversion efficiency was improved. This is thought to be due to the improvement in long wavelength sensitivity and the improvement in electron and hole mobilities in the microcrystalline layer.

FIG. 2 is a schematic sectional view showing a second embodiment of the present invention. In FIG. 2, reference numeral 201 denotes an n-type wafer substrate. 202 is an i-type microcrystalline silicon layer, 203
Denotes an i-type hydrogenated amorphous silicon layer, 204 denotes a p ⁺ -type hydrogenated amorphous silicon layer , and 205 denotes a transparent electrode. In this embodiment, the portion n of the pin structure is constituted by a wafer. Light through the transparent electrode 20 5 enters from the p ⁺ layer, the carriers generated in the i layer, the internal electric field, the electrons in the n-type wafer side, holes in the p-layer side,
Each drifts, and as a result, an electromotive force is generated between p ⁺ and n.

Next, a method of manufacturing the photoelectric conversion device of this embodiment will be described along with its steps. Each film was formed using the apparatus shown in FIG.

First, an n-type wafer 201 whose surface has been cleaned
Is attached to the cathode in the reaction chamber 800,
The air was sufficiently exhausted by an exhaust pump 809 to 10 ^-6 Torr. The substrate temperature was 250 ° C.

Next, the microcrystalline silicon layer 202 and subsequently the hydrogenated amorphous silicon layer 2 are formed by the film forming method according to the present invention.
03 is deposited. The substrate temperature was kept at 250 ° C. Hydrogen plasma discharge by RF discharge was used to produce atomic hydrogen.

First, the valves 860 and 861 were opened, and 170 sccm of H ₂ gas was flowed into the reaction chamber. After connecting the three-way valve 813 between the deposition gas introduction pipe 811 and the exhaust pipe 814, the valves 820 and 822 are opened,
30 sccm of an SiH ₄ gas was flowed into the film formation gas introduction pipe 811. The pressure at this time was 0.5 Torr. In this state, an RF power of 50 mW / cm ² was applied to start hydrogen plasma discharge. Next, by switching the three-way valve 813 by a computer, film formation and hydrogen plasma irradiation are repeated.

The film forming time t _D is constant at 10 seconds, and is set at 10 °
. At this time, the crystallite size was approximately 300 °. The total number of steps was 100, and the thickness of the microcrystalline layer was 1000 °. At this time, the hydrogen concentration in the film was 3%.

After the hydrogen plasma discharge in the final step is completed, the valve 813 is switched, and SiH ₄ is introduced into the chamber. Thereafter, a discharge is started, and a hydrogenated amorphous silicon layer is continuously formed at 3000 °. Preferably,
It is preferable to form a film while maintaining discharge. At this time, the optical band gap of the hydrogenated amorphous silicon layer was 1.8 eV. In this embodiment, the hydrogen dilution rate is SiH
₄ / H ₂ = 3/17, and the photoelectric characteristics of the continuous film were good.

Next, ap ⁺ -type layer 204 was formed. After closing the valves 820 and 822 and closing the valves 860 and 862 to stop the silane gas and the hydrogen gas, the chamber was evacuated to a degree of vacuum of 10 ^-6 Torr or less. Substrate temperature 2
After changing to 00 ° C., SiH ₄ flowed gas 10sccm and H ₂ B ₂ H ₆ gas 10sccm and H ₂ gas 100sccm diluted to 1% with the gas, while maintaining the pressure to 1 Torr,
The temperature was maintained until the substrate temperature became constant. Thereafter, an RF power of 50 mW / cm ² was applied and plasma discharge was performed for 10 minutes to form a p ⁺ -type layer at 500 °. After closing each valve and stopping the gas, the inside of the chamber was evacuated to 10 ^-6 Torr or less.

Finally, a transparent conductive film (ITO) was used as the upper electrode.
A film 205 was formed at 700 °.

As an effect of the present embodiment, the interface between the microcrystalline layer 202 and the n-type wafer 201 is formed well, and loss of carriers due to recombination at the bonding surface can be suppressed. Carriers drifting from the photoelectric conversion layer diffuse in the n-type wafer 201. At this time, since the diffusion length of the carriers in the n-type wafer is long, the rate at which carriers recombine during diffusion can be reduced. As a result, a device having a higher conversion efficiency than that of Example 1 was obtained. Although the size of the substrate is limited, the structure is optimal for the purpose of improving efficiency with a small-area solar cell.

[0074]

As described above, according to the present invention,
By using a microcrystalline silicon layer as a narrow optical bandgap material and creating this microcrystalline layer in a repetitive film forming method of alternately forming a film and exposing to atomic hydrogen, a simpler process than in the past, A photoelectric conversion device showing good photoelectric characteristics was obtained.

Further, since the process is simplified, the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a photoelectric conversion device according to the present invention.

FIG. 2 is a view showing a second embodiment of the photoelectric conversion device according to the present invention.

FIG. 3 is a diagram showing a conventional photoelectric conversion device.

FIG. 4 is a diagram showing an energy band of the present embodiment.

FIG. 5 is a diagram showing an energy band of a conventional example.

FIG. 6 is a diagram showing spectral sensitivity.

FIG. 7 is a diagram showing conversion efficiency.

FIG. 8 is an apparatus diagram for realizing the present invention.

FIG. 9 is a diagram showing a relationship between a substrate temperature and a hydrogen concentration in a film according to the present invention and a case according to a normal GD method.

FIG. 10 shows a relationship between hydrogen concentration in a film and t _A.

FIG. 11 shows the relationship between the hydrogen concentration in the film and the film thickness in each step.

FIG. 12 shows the relationship between the crystal grain size and t _A.

FIG. 13 shows a relationship between a band gap and a hydrogen concentration in a film.

[Explanation of symbols]

101,301 Glass substrate 201 Wafer substrate 102,302 Lower electrode 103,303 n ⁺ -type hydrogenated amorphous silicon layer 104,202 Microcrystalline silicon layer 105,203,304 i-type hydrogenated amorphous silicon layer 106,204,305 p ⁺ Type hydrogenated amorphous silicon layer 107, 205, 306 Transparent electrode Ap region Bi i-type hydrogenated amorphous silicon layer C microcrystalline silicon layer D n region F Fermi level

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masato Yamanobe 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-63-274184 (JP, A) JP-A-2 -42765 (JP, A) JP-A-2-218175 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 31/04-31/078 H01L 21/20-21/208

Claims (1)

(57) [Claims] 1. A semiconductor layer of a first conductivity type, an undoped silicon layer provided on the semiconductor layer of the first conductivity type, and undoped hydrogen provided on the silicon layer Having a hydrogenated amorphous silicon layer and a second conductive type semiconductor layer different from the first conductive type provided on the hydrogenated amorphous silicon layer. There has a configuration in which the incident, the silicon layer which is not the doping, the optical band gap, wherein a narrow than the optical band gap of the doped non hydrogenated amorphous silicon layer microcrystalline silicon layer photoelectric conversion device The manufacturing method of
Te, depositing a non-single-crystal silicon, non-single binding that the deposition
Exposing crystalline silicon to atomic hydrogen.
Photoelectric conversion device for forming the microcrystalline silicon layer
Manufacturing method.